Improved flow through the Halfweg Locks

The Halfweg lock complex plays a crucial role for water management in the Haarlemmermeerpolder. To ensure better functioning of the pumping station behind it, the flow capacity of the lock complex had to be increased. During heavy rainfall, the water often gets stuck because the lock complex does not allow the water supply to the storage basin pumping station to pass through properly. This causes too low a water level in Zijkanaal F, resulting in inconvenience and a less functioning pumping station. In some cases, the storage basin pumping station even has to stop.

Hoogheemraadschap van Rijnland (HHR) asked Iv to jointly determine a preferred alternative for the culvert from several variants during the exploration phase. Iv then elaborated this alternative into a preliminary design in the planning phase, with a level of detail suitable for applying for an environmental permit.

For the Municipality of Haarlemmermeer, the lock complex holds historical significance and tourist value. The complex is a municipal monument and includes a national monument in the form of an old railway bridge. The design and construction work had to be carried out within a small area, with limited available data on the historical structure. This made assessing the strength and behaviour of the complex particularly challenging.

To improve the flow capacity of the lock without compromising its monumental character, a new passage was created in the eastern lock island. The sheet pile walls were reinforced with an underwater concrete floor serving as a support, while the lock and wing walls and the sandstone capstones were restored as much as possible. Collaboration with TAK Architects and the heritage committee was essential in obtaining approvals and successfully preserving the historical value.